Method of making capsules



May 23, 1944. 1.. P. MILLER METHOD OF MAKING CAPSULES Filed Jan. 28, 194i LIQUID GELATIN PRESS COLD AIR

"INVENTOR. LOUIS RMILLER BY M ATTORNEYS Patented May 23, 1944 m-z'rnon or MAKING osrsnnss Louis 1r. Miller, Cleveland Heights, Ohio, assignor to American Home Products Corporation, Jersey City, N. 1., a corporation of Delaware Application Ianuary 23, 1041, Serial No. 210,311

2 Claims.

Thepresent invention relates to an improved method of making capsules for containing food and pharmaceutical materials, and the like. Such capsules are composed of a water-soluble substance, viz., gelatin, which forms the shell or container, per se, and are filled with a pharmaceutical material. My invention is particularly applicable to the fabrication of such capsules which are adapted to contain liquid or semi-liquid filling materials wherein the gelatin shell is integral and continuous in order properly to seal the material contained therein.

Such capsules of the liquid or semi-liquid filled type are'presentlymade by a process involving first, the formation of the liquid or molten gelatin into solid sheets or bands; secondly, the interposition of the liquid or semi-liquid filling material between two of such sheets; and finally, the pressing together of a sandwich" of gelatin sheets and filling material between capsule-forming dies whereby portionsof the gelatin sheets are deformed or molded into opposed die cavities forming the two halves'of the capsule, with the filling material enclosed or trapped therein, and simultaneously sealing or bonding the meeting edges of these two halves together. of properly controlling the physical properties of the gelatin and the gelatin sheets so that they erties of flexibility and adhesion-which have been so highly desired in the gelatin and result in the increased efficiency and economy of the capsulemaking process, a whole. T

To the accomplishment of the foregoing and related ends, said invention, then consists of the steps hereinafter fully described and particularly pointed out in the claims.

The annexed drawing and the following description set forth in detail one approved method of carrying out the invention, such disclosed method,-however, constitutingbutone of various ways in which the principle of theinvention may be The problem 7 will accommodate the dual functions of being i properly and uniformly formed in the die cavities and efiiciently bonded or sealed, has been a difllcult one in the capsule-making industry. A very close control of the temperature of the gelatin as it passes through the various formation stages from liquid to the completed capsule has been a subject of considerable effort and research. (For example, see article by A. L. Lane in "Electrical World," vol. III, p. 584). It has heretofore been regarded necessary to subject the gelatin sheets or bands, .after formation and solidification from the liquid or molten gelatin, to a heating action whereby the adhesive properties and the plasticity of the gelatin is in creased in order to obtain a satisfactory forming and sealing or bonding of the halves of the capsule. I have discovered that just the opposite procedure produces the desired results in the forming and bonding ability of the gelatin, and to a greater and more efficient degree than has heretofore been achieved. My invention is, therefore, based upon the unusual and unexpected discovery that the sudden coolingof the gelatin after it is transformed from its liquid state to sheet form and prior to forming and bonding into capsules, produces the physical prop- Insaidannexed drawingr Fig. l is a flow sheet illustrating the various steps of the capsule-making process andwith the improvement of my invention as applied thereto; Fig. 2 is an enlarged, detailed sectional view illustrating the step of the process wherein the liquid or molten gelatin is formed into a solid sheet or band; Fig. 3 is another enlarged, sectional view illustrating the sandwich of gelatin sheets and filler placed in position between the capsule-forming die plates; and- Fig. 4 is a similar view to Fig. 3 but showing the die plates in closed position, wherein the resultant capsule has been formed. I Now referring more particularly to Fig. 1, the first stage of the process involves a provision of a quantity of liquid or molten gelatin which is suitably prepared and contained in a tank or 1 reservoir I;

A temperaturein the range-of 140 .to 160- F. is maintained in the tanki to insure the moltenstate of the gelatin; The liquid gelatin from the tank I is next poured upon a sheetforming surface, such as that of "the rotating drum 2. As the liquid gelatin is deposited upon the surface of the drum 2 which is maintained at a temperature of F., it is suddenly and rapidly cooled to a point substantially below its solidification temperature or melting point, by means of a body of cold, refrigerated air, introduced through the duct 3 and led around the periphery of the drum 2 by means of the enclosing housing 4. The range of this cooling temperature is from 45 to 65 F. As the melt ing point of gelatin is in the range of to F., (depending on its quality) it will be seen that this cooling action results in a very rapid freezing and sudden decrease in the temperature of the liquid gelatin, particularly since the latter is in sheet or film form and, therefore, has a very large area exposed to the action of the cooling air.

Referring particularly to Fig. 2, the manner in which the liquid gelatin, as indicated at 5, flows onto the drum 2 under the pouring gate 6 and is then suddenly cooled and solidified to form the solid sheet I, is illustrated in greater detail. The stippled and the cross-hatched sections represent the approximate points of formation of the liquid and solid states, respectively, of the gelatin. The solid band or sheet of gelatin 1 is then led to the cutting table or conveyor 8 where it is cut into individual. sheets by means of the cutting mechanism 8. One of these individual sheets II is placed on the upper face the lower-forming die plate II, aquantity of liquid or semi-liquid filling material is deposited from the tank II on the surface of the sheet I0 and another individual sheet it placed on the top thereof. Thus, a "sandwich resting upon the top of the lower die plate II is formed which comprises outer layers I0 and ll of gelatin sheets and the intermediate layer of filling ma.-

emulsion or the like.

ceuticai capsules produces capsules which are of uniform size and capacity. The unexpected and remarkable results in the improvement of the capsule-forming properties of the gelatin sheets, produced according to my process is, of course, an important factor in obtaining this uniformity and control of capsule size. If the sheet is too hard terial, such as cod-liver oil, a pharmaceutical It will be noted that the sheet I of gelatin hasa cold air side marked'A, in Fig. 2, and a drum side, marked B. 7 It has been found that the manher in which these respective sides'A and H of the individual sheets II and I4 are placed with respect to each other in the formation of the sandwich is an important requisite. Thus, as shown in Fig.

3, the cold air sides" A of the sheets I0 and I4 respectively, are placed outermost or in a position where they will be contacted by the die plates I I and I6, and the "drum sides" B of the sheets are placed innermost where they will contact each other.

The lower die plate II is then placed ina press I! and the upper die plate I. pressed down against it. The die plates II and I8 contain a multiplicity of registering die cavities I1 and I I (usually of cy- 'lindrical cross-sectional form), respectively, into which portions of the gelatin sheets II and Il, being of the proper and desired flexibility, are deformed and forced to form the two halves I9 and 20 01' the capsule, and with the body of fllling material I3- trapped therein. The projecting lips or flanges II and 22, during the final compression or closing stage of the die plates II and I6, force the meeting edges of the molded halves I9 and 20 togetherfthereby enacting a proper seal or bond between these halves to form a complete, continuous and integral capsule shell. The flanges Ill and 22 also simultaneously cut through the body of the gelatin sheets leaving a piece 23 of reticulated form whichv is commonly termed the net.

My above described process of making pharma and brittle, it will not properly enter the forming die cavities, and by the same token, if it is too soft or plastic, it will enter the die cavities to a greater than the desired extent.

I am unable to ascribe any scientific theory or principle to the novel results achieved by my invention. Sufl ice it to say that the sudden cooling of the liquid gelatin as it is transformed from liquid to solid form, and to a temperature well below the solidification temperature of the gelatin,

probably imparts a "temperature shock" which has a curing effect upon the gelatin sheet which develops a heretofore unknown property of gelstin, because it has previously been supposed that gelatin is of a thermoplastic nature and requires heating in order to render it elastic and adhesive.

The values given herein for the various temperatures will be understood to be by the way of example, and that in actual practice they may be subject to reasonable variations, all within the proper scope and spirit of my invention.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the method herein disclosed, provided the step or steps stated by any of the following claims or the equivalent of such stated step or steps be employed.

I, therefore, particularly point out and distinctly claim as my invention:

1. In the method of makinggelatin capsules the steps which comprise, heating. gelatin to a temperature range of about 140 F, to about 160 F.,

to reduce it to molten form, flowing such molten gelatin onto asheet forming surface maintained at 90 F., simultaneously cooling-the exposed side oi the sheet to a temperature of from about 5" F. 

